Validation of a Lagrangian dispersion model and its application to monitor a power plant

In order to evaluate the dose loads due to accidental releases at the nuclear power plant Hamm-Uentrop a monitoring system has been developed working in real-time. Meteorological data as well as emission data will be averaged to 10 min mean data and forwarded to the authority. If the authority realizes the exceeding of a given threshold a computer code to determine the dose loads will be initiated: first, the locally varying windfield will be determined by means of a mass consistent windfield model. These data will be inputed into a particle (Lagrangian) model to determine the ground- and airborne close-to-the-ground concentration pattern for aerosols, iodine and noble gas. Here, precipitation is being considered. The concentration pattern are inputed into a dose model to determine the whole body and thyroid loads for adults and 1 year old small children. The exposition paths considered are inhalation, ground contamination and cloud shine. The computer comes to a stop when the corresponding plots (windfield, windprofile, concentration- and dose load distribution) have been displayed on the terminal. It resumes the computation at the arrival of a new data telegramme at the computer consisting of meteorological and emission data for a new episode lasting 10 minutes. Here, the results of the last computation are taken into account. The computing time for the windfield, concentration and dose as well as the plotting at a main frame is less than 3 minutes. The data transfer from a main frame to the authority takes less than 10 minutes so that real time monitoring is assured